Electron emitting method of electron emitter

Abstract

An electron emitter has an emitter section formed on a substrate, and a cathode electrode and an anode electrode formed on a same surface of the emitter section. A slit is formed between the cathode electrode and the anode electrode. A drive voltage from a pulse generation source is applied between the cathode electrode and the anode electrode, and the anode electrode is connected to the ground. A collector electrode is provided above the emitter section at a position facing the slit. The collector electrode is connected to a bias voltage source through a resistor. The emitter section is made of a piezoelectric material.

1. A method of emitting electrons from an electron emitter including an emitter section made of a dielectric material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method comprising the steps of:
 polarizing said emitter section in one direction; and 
 applying an electric field beyond a coercive field to said emitter section through said first and second electrodes to reverse polarization of said emitter section for emitting electrons, 
 wherein a voltage change between said first and second electrodes is 20 V or less at the time electrons are emitted, thereby preventing positive ion damage to the electrodes. 
 
   
   
     2. A method of emitting electrons according to  claim 1 , wherein said emitter section is made of a piezoelectric material. 
   
   
     3. A method of emitting electrons according to  claim 2 , wherein said electric field beyond said coercive field is applied to said emitter section within a certain period for emitting electrons. 
   
   
     4. A method of emitting electrons according to  claim 2 , wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and
 said polarization reversal of said emitter section for emitting electrons is performed by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period. 
 
   
   
     5. A method of emitting electrons according to  claim 4 , wherein a level of said second voltage is controlled so tat said electric field beyond said coercive field is applied to said emitter section within a certain period from the beginning of said second period. 
   
   
     6. A method of emitting electrons according to  claim 1 , wherein said emitter section is made of an anti-ferroelectric material. 
   
   
     7. A method of emitting electrons according to  claim 6 , wherein said electric field applied to said emitter section has a level for inducing phase transition of said emitter section into a ferroelectric material within a certain period, and changing polarization of said emitter section for emitting electrons. 
   
   
     8. A method of emitting electrons according to  claim 6 , wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and
 phase transition of said emitter section into a ferroelectric material is induced, and polarization of said emitter section is changed by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period. 
 
   
   
     9. A method of emitting electrons according to  claim 8 , wherein said first voltage applied between said first electrode and said second electrode in said first period is 0V, and polarization of said emitter section is reset. 
   
   
     10. A method of emitting electrons according to  claim 8 , wherein a level of said second voltage is controlled so that phase transition of said emitter section into a ferroelectric material is induced within a certain period from the beginning of said second period, and an electric field is applied to said emitter section to change polarization of said emitter section for emitting electrons. 
   
   
     11. A method of emitting electrons according to  claim 8 , wherein a level of said second voltage is controlled at the beginning of said second period to repeat a series of cycle in which said second voltage reaches a level required for electron emission and the voltage between said first electrode and said second electrode drops due to electron emission to a threshold level for resetting polarization of said emitter section. 
   
   
     12. A method of emitting electrons according to  claim 1 , wherein said emitter section is made of an electrostrictive material. 
   
   
     13. A method of emitting electrons according to  claim 12 , wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and
 polarization of said emitter section is changed for emitting electrons by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period. 
 
   
   
     14. A method of emitting electrons according to  claim 13 , wherein said first voltage applied between said first electrode and said second electrode in said first period is 0V, and polarization of said emitter section is reset. 
   
   
     15. A method of emitting electrons according to  claim 13 , wherein a level of said second voltage is controlled so that an amount of polarization in the emitter section within a certain period from the beginning of said second period is controlled, and the number of emitted electrons is controlled. 
   
   
     16. A method of emitting electrons according to  claim 13 , wherein a level of said second voltage applied at the beginning of said second period is controlled so that electron emission continues by slight fluctuation of the voltage between said first electrode and said second electrode. 
   
   
     17. A method of emitting electrons according to  claim 1 , wherein
 said first electrode is formed in contact with said emitter section; 
 said second electrode is formed in contact with said emitter section; and 
 a slit is formed between said first electrode and said second electrode. 
 
   
   
     18. A method of emitting electrons according to  claim 17 , wherein polarization reversal or polarization change occurs in an electric field E applied to said emitter section represented by E=Vak/d, where d is a width of said slit, and Vak is a voltage between said first electrode and said second electrode. 
   
   
     19. A method of emitting electrons according to  claim 18 , wherein said voltage Vak is less than a dielectric breakdown voltage of said emitter section. 
   
   
     20. A method of emitting electrons according to  claim 1 , wherein said first electrode is formed on a first surface of said emitter section, and said second electrode is fanned on a second surface of said emitter section. 
   
   
     21. A method of emitting electrons according to  claim 20 , wherein polarization reversal or polarization change occurs in an electric field E applied to said emitter section represented by E=Vak/h, where h is a thickness of said emitter section between said first electrode and said second electrode, and Vak is a voltage between said first electrode and said second electrode. 
   
   
     22. A method of emitting electrons according to  claim 21 , wherein said voltage Vak is less than a dielectric breakdown voltage of said emitter section. 
   
   
     23. A method of emitting electrons according to  claim 1 , wherein said electric field is applied between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode to reverse or change polarization of at least a portion of said emitter section; and
 the polarization reversal or polarization change induces emission of electrons in the vicinity of said first electrode. 
 
   
   
     24. A method of emitting electrons according to  claim 1 , wherein said electric field is applied between said first electrode and said second electrode to reverse or change polarization of at least a portion of said emitter section;
 the polarization reversal or polarization change causes positive poles of dipole moments in the vicinity of said first electrode to be oriented toward said first electrode, inducing emission of primary electrons from said first electrode; and 
 said emitted primary electrons impinge upon said emitter section to induce emission of secondary electrons from said emitter section. 
 
   
   
     25. A method of emitting electrons according to  claim 24 , wherein said first electrode, said emitter section, and a vacuum atmosphere define a triple point; and
 primary electrons are emitted from a portion of said first electrode in the vicinity of said triple point, and said emitted primary electrons impinge upon said emitter section to induce emission of secondary electrons from said emitter section. 
 
   
   
     26. A method of emitting electrons from an electron emitter including an emitter section made from a piezoelectric material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method steps comprising:
 polarizing said emitter section in one direction by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period; and 
 reversing polarization of said emitter section by applying a second voltage beyond a coercive field between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period, causing said emitter section to emit electrons. 
 
   
   
     27. A method of emitting electrons from an electron emitter including an emitter section made from an antiferroelectric material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method steps comprising:
 polarizing said emitter section in one direction; and 
 applying an electric field beyond a coercive field to said emitter section through said first and second electrodes to reverse polarization of said emitter section for emitting electrons; 
 wherein said electric field applied to said emitter section has a level for inducing phase transition of said emitter section into a ferroelectric material within a certain period, and changing polarization of said emitter section for emitting electrons. 
 
   
   
     28. A method of emitting electrons from an electron emitter including an emitter section made from an electrorestrictive material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method steps comprising:
 polarizing said emitter section in one direction by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period; and 
 reversing polarization of said emitter section by applying a second voltage beyond a coercive field between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period, causing said emitter section to emit electrons. 
 
   
   
     29. A method of emitting electrons from an electron emitter including an emitter section made from a dielectric material, a first electrode in contact with a first surface of said emitter section, and a second electrode in contact with a second surface of said emitter section, said method steps comprising:
 polarizing said emitter section in one direction; and 
 applying an electric field beyond a coercive field to said emitter section through said first and second electrodes to reverse polarization of said emitter section for emitting electrons, 
 wherein polarization reversal or polarization change occurs in an electric field E applied to said emitter section represented by E=Vak/h, where h is a thickness of said emitter section between said first electrode and said second electrode, and Vak is a voltage between said first electrode and said second electrode. 
 
   
   
     30. A method of emitting electrons from an electron emitter including an emitter section made from a dielectric material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method steps comprising:
 polarizing said emitter section in one direction; and 
 applying an electric field beyond a coercive field to said emitter section through said first and second electrodes to reverse polarization of said emitter section for emitting electrons, 
 wherein polarization reversal and electron emission occur at a voltage of less than 100 V.